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Synfacts 2013; 9(1): 0003
DOI: 10.1055/s-0032-1317722
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York

Synthesis of (+)-Lithospermic Acid

Contributor(s):
Philip Kocienski
Ghosh AK, * Cheng X, Zhou B. Purdue University, West Lafayette, USA
Enantioselective Total Synthesis of (+)-Lithospermic Acid.

Org. Lett. 2012;
14: 5046-5049
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Further Information

Publication History

Publication Date:
17 December 2012 (online)

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Key words

lithospermic acid - HIV integrase - organocatalysis - asymmetric oxa-Michael reaction - oxidative ring contraction - C–H activation

Significance

This elegant synthesis of the HIV integrase inhibitor lithospermic acid features (1) an enantioselective intramolecular oxa-Michael reaction; (2) an oxidative ring contraction of the chromanone F; and (3) an intermolecular palladium-catalyzed C–H olefination used to append acrylate ester K to J.


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Comment

The enantiomeric ratio of F improved to 99:1 after one recrystallization. The presence of the two electronegative bromine atoms on chromanone F were essential for the success of the oxidative ring contraction mediated by phenyl­iodonium bis(trifluoroacetate).


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